Noncarious Cervical Lesions, NCCLs: Causes, Abfraction, Occlusion, Gingival Recession, and When to Restore
Few findings in restorative dentistry invite more confident explanations than the noncarious cervical lesion. A wedge shaped defect appears at the cervical surface of a premolar, often beside gingival recession, and the diagnosis seems obvious. One dentist sees toothbrush abrasion. Another sees erosion. Another sees abfraction from occlusal stress. The problem is that the lesion is usually telling a more complicated story than any single label can capture.
The safest and most useful term is noncarious cervical lesion, or NCCL. That description names what is present without pretending that its cause has already been proven. The literature increasingly supports a multifactorial model. Chemical degradation, mechanical wear, brushing behavior, dentifrice abrasivity, gastric or dietary acid exposure, tooth position, periodontal anatomy, and possibly occlusal loading may contribute in different proportions in different patients. What the evidence does not support is looking at a wedge shaped lesion and declaring, with certainty, that occlusion caused it.
That distinction matters because the abfraction explanation is seductive. Teeth flex under load. Engineering models show that stress can concentrate near the cervical region. Some clinical studies find associations between NCCLs and wear facets, parafunction, heavy contacts, or other occlusal variables. A 2017 systematic review found that many included studies reported some association between occlusal stress and NCCLs. Yet no clinical study in that review showed that occlusal stress alone caused the lesion. Other systematic reviews of human clinical studies found the association inconsistent or unconfirmed. The 2018 periodontal World Workshop went further, concluding that there was no credible evidence that traumatic occlusal forces cause NCCLs and that the classic abfraction mechanism had not been demonstrated clinically.
That does not mean occlusion is irrelevant. Excessive forces can produce mobility, fremitus, widened periodontal ligament spaces, discomfort, migration, wear, and other signs of injury. Occlusal loading is biologically plausible as one contributor to cervical stress, and it may interact with acid softened tooth structure and mechanical wear. But plausible is not the same as proven. In practice, a genuine occlusal problem should be treated because the occlusal problem itself warrants treatment, not because the dentist has promised the patient that equilibration, orthodontics, or a nightguard will stop an NCCL.
The same caution applies to toothbrushing. Traumatic brushing has long been blamed for both recession and cervical lesions, and there are studies associating NCCLs with brushing frequency, horizontal scrubbing, harder bristles, and other behaviors. Yet the evidence is inconsistent. A systematic review of traumatic toothbrushing concluded that the data supporting or refuting brushing as a cause of recession and NCCLs remained largely inconclusive. Brushing alone often fails to reproduce the lesions seen clinically, while abrasion becomes more damaging when enamel and dentin have already been softened by acid. The more realistic clinical model is interaction, not monocausation.
That is why the history matters. Ask about acidic beverages, citrus, sports drinks, reflux, vomiting, xerostomia, brushing technique, dentifrice, parafunction, sleep habits, tooth position, orthodontic history, recession, and sensitivity. Look at the entire mouth rather than the isolated defect. A patient may have a heavy hand with a toothbrush, a highly abrasive toothpaste, frequent acid exposure, thin facial tissues, recession, and bruxism all at once. Finding one of those factors does not prove it created the lesion, but it can identify something worth modifying.
Morphology helps with treatment planning, but it does not reliably reveal etiology. NCCLs are commonly wedge shaped or saucer shaped, and they occur disproportionately on facial surfaces and premolars. Longitudinal work shows that many progress slowly. Saucer shaped lesions tend to spread more in height, while wedge shaped lesions are more likely to increase in both height and depth. Some lesions appear to move through active and relatively inactive periods. That makes serial observation valuable. Photographs, scans, study models, and reproducible measurements can tell the dentist whether a lesion is actually changing instead of forcing a decision based on one snapshot in time.
This leads to the most important clinical question. Does the lesion need to be restored at all?
Many do not. A stable, cleansable, asymptomatic lesion with little structural risk may be better monitored than filled. Restoration becomes more reasonable when there is documented progression, significant sensitivity, unacceptable esthetics, food or plaque retention, loss of cervical anatomy, or concern about tooth strength. One recent clinical review suggested that wedge shaped lesions approaching about 1.5 mm in axial depth deserve greater attention because deeper defects may concentrate stress and threaten structural integrity. That figure should not be treated as a rigid cutoff, but it is a useful reminder that lesion depth matters.
Once the decision to restore is made, the next problem is adhesion. Longstanding NCCLs frequently contain sclerotic, hypermineralized dentin with partially or completely occluded dentinal tubules. That substrate is not normal freshly cut dentin. It can resist etching and make adhesive penetration less predictable. Add limited enamel, difficult gingival isolation, moisture contamination, and a margin that may sit close to or below the gingiva, and it becomes easy to understand why cervical composites can be technique sensitive.
Recent laboratory evidence suggests that gentle mechanical roughening and prolonged phosphoric acid conditioning may improve bond strength to sclerotic dentin, with 37 percent phosphoric acid showing the most consistent support among the pretreatments studied. But the evidence remains low quality and largely laboratory based. The larger lesson is more important than any exact etching time. A cervical restoration that debonds does not prove that tooth flexure caused the failure. The substrate itself may have been difficult to bond, isolation may have been compromised, the adhesive interface may have degraded, or multiple factors may have acted together.
Material choice should follow the clinical situation. Resin composite offers excellent esthetics and contour when isolation is reliable. Glass ionomer and resin modified glass ionomer remain useful when moisture control is difficult or the margin extends onto root dentin. No material eliminates the need for careful case selection, surface preparation, finishing, and patient communication. The patient should understand that restoring an NCCL can start a restorative maintenance cycle, which is another reason not to fill a lesion simply because it exists.
Gingival recession adds another layer, and it should be diagnosed separately from the NCCL. Recession and cervical lesions frequently coexist, but one does not automatically cause the other. Modern periodontal literature treats these as combined defects because the gingival margin and tooth surface can each require separate decisions. The clinician should assess recession type, gingival phenotype, whether the cemento enamel junction can still be identified, and whether the cervical defect has a significant step or deep V shaped form.
Shallow combined defects may need periodontal root coverage without any restoration at all. As the lesion becomes deeper, destroys the cemento enamel junction, or develops a pronounced step, combined restorative and periodontal treatment becomes more logical. In selected deep defects, partial composite reconstruction can restore lost coronal anatomy and recreate a useful cervical reference before root coverage surgery. Thin gingival tissue may strengthen the indication for connective tissue augmentation, while thicker tissue may permit a less invasive periodontal approach. Again, the treatment plan follows anatomy and symptoms, not a presumed story about what caused the lesion.
This is also where patient communication can become much better. Instead of telling the patient, “You are brushing too hard,” or, “Your bite is breaking your teeth at the gumline,” explain that these lesions usually develop from a combination of factors and that the exact contribution of each factor cannot always be determined. Then show the patient what is modifiable. Reduce acid exposure when it is present. Improve brushing technique without discouraging effective plaque control. Address significant reflux medically. Treat true occlusal trauma, parafunction, or malocclusion when independently indicated. Manage recession when it creates sensitivity, esthetic concerns, or periodontal risk. Restore the tooth when the lesion itself justifies restoration.
That approach is not indecisive. It is more precise. It avoids overtreatment, avoids unsupported promises, and makes the treatment plan easier for the patient to understand. It also protects the dentist from the trap of turning a hypothesis into a diagnosis.
The practical rule is simple. Call the lesion what it is, an NCCL. Look for multiple contributors. Separate etiology from the decision to restore. Separate recession from the cervical defect. Treat genuine occlusal, periodontal, behavioral, and restorative problems on their own merits. And when a lesion is stable, cleansable, asymptomatic, and structurally safe, remember that monitoring is still treatment.
If we cannot prove exactly what caused an NCCL, should we be more comfortable doing less until the tooth gives us a reason to do more?
Join the Conversation!